In general, a conventional bicycle has a rear wheel drive system that turns a rear wheel by using a chain connected to a crankset, more specifically, when a user pedals in order to turn the crankset using his or her legs, the chain connected to the crankset rotates, thereby rotating the rear wheel, thus propelling the bicycle.
However, the conventional bicycle is problematic in that the conventional bicycle is operated only using the rear wheel drive system, thereby the bicycle is driven only by user's leg power, thus when going up a sloping hill or having a heavy load on the bicycle, it is difficult to propel the bicycle efficiently. The conventional bicycle is also problematic in that when using the bicycle for the purpose of exercising, only the user's lower body is used to rotate the crankset by pushing pedals attached thereto, and thus the user's arms and upper body are not exercised.
As documents of a related art, Korean Utility Model Registration No. 20-0418333 and Korean Patent No. 10-0776575 disclose devices to improve the rear wheel drive system.
However, each of the conventional rear wheel drive systems disclosed in the Korean utility model and Korean Patent is problematic in that it is difficult to generate front wheel driving force while steering a bicycle because the conventional rear wheel drive system employs a method of moving a steering part from side to side or pulling the steering part in order to steer the bicycle and drive a front wheel, simultaneously.